Add `InSample` resampling strategy

[ablaom]

When you want to train on all specified data and test on the same data.

So,

e = evaluate(model, X, y, resampling=InSample(), measure=l1)
e.measurement[1]

is equivalent to:

mach = machine(model, X, y) |> fit!
yhat = predict(mach, X)
l2(yhat, y)

Which is even more convenient when there is battery measures to be evaluated.